1. Field of the Invention
The present invention relates to a photoacoustic signal processing device, a photoacoustic signal processing system, and a photoacoustic signal processing method, and particularly, to a photoacoustic signal processing device, a photoacoustic signal processing system, and a photoacoustic signal processing method which detect a photoacoustic wave generated in a subject after light emission to the subject and generate a photoacoustic image.
2. Description of the Related Art
As one image inspection method which can noninvasively inspect a state inside a living body, an ultrasonography method is known. In ultrasonography, an ultrasound (ultrasonic wave) probe which can transmit and receive an ultrasonic wave is used. If an ultrasonic wave is transmitted from the ultrasound probe to the subject (living body), the ultrasonic wave travels inside the living body, and is reflected from a tissue interface. The reflected ultrasonic wave is received by the ultrasound probe, and a distance is calculated based on the time until the reflected ultrasonic wave returns to the ultrasound probe, whereby it is possible to image a status inside the living body.
Furthermore, photoacoustic imaging which images the inside of a living body using a photoacoustic effect is known. In general, in photoacoustic imaging, the inside of the living body is irradiated with a pulse laser beam, such as a laser pulse. Inside the living body, a living body tissue absorbs the energy of the pulse laser beam, and an ultrasonic wave (photoacoustic wave) is generated due to adiabatic expansion caused by the energy of the pulse laser beam. The photoacoustic wave is detected by an ultrasound probe or the like, and a photoacoustic image is constructed based on the detection signal, whereby it is possible to visualize the inside of the living body according to the photoacoustic wave.
JP2005-342128A (Paragraph [0016]) describes that a puncture needle punctured into a subject is imaged by an ultrasound diagnostic apparatus. In general, the puncture needle is made of a metal, such as stainless steel, and the intensity of a reflected ultrasonic wave reflected from the puncture needle is stronger than the intensity of a reflected ultrasonic wave reflected from a living body tissue in the subject, and the presence of the puncture needle on the ultrasound image can be confirmed. In the observation of the puncture needle, it is particularly important to recognize where the tip of the needle is positioned. In JP2005-342128A (Paragraph [0016]), the tip portion of the needle is subjected to special processing for enhancing the reflection of the ultrasonic wave, and the intensity of a reflected ultrasonic wave reflected from the tip portion of the puncture needle is more enhanced than the intensity of a reflected ultrasonic wave reflected from a different portion of the puncture needle.
JP2013-511355A (Paragraph [0096], FIG. 7) describes that a photoacoustic wave is generated from a needle using a photoacoustic effect. In JP2013-511355A (Paragraph [0096], FIG. 7), a pulse laser beam is applied directly to the needle to generate a photoacoustic wave. The needle functions as a wave guide, and the generated photoacoustic wave propagates from a shaft and the tip. The photoacoustic wave emitted from the needle is detected by a probe.